The invention relates to pearl luster pigments which are based on mica flakes coated with metal oxides, in particular titanium dioxide, and have an improved stability in glazes and enamels.
The previously known metal oxide/mica pigments are in many cases annealed during their preparation at temperatures of up to 1,000.degree. C. and are therefore to be regarded as extremely stable to heat. Nevertheless, these pigments usually cannot be used in decorative glazes or enamel, since under the stoving conditions of about 750.degree.-850.degree. C. customary here the pigments are so severely attacked by the aggressive enamels that the pearl luster effect is very greatly impaired. Only pigmenting of decorative enamels on glass, for which lower temperatures of about 500.degree.-750.degree. C. are used, has so far been successfully carried out.
There was therefore a need for pigments with which decorative pearl luster effects can also be produced in the glazes and enamels stoved at high temperatures.